Electrodeposition of cadmium



July 6, 1937, .J. A. HENRICKS, JR f 2,085,750

ELECTRODEPOSI TION OF 'CADMIUM.

Filed Oct. 17, 1935 flldaeets lAcataidohyde I Kea/don es I Paraldoi rem?) Arnoreaction Product Cyanidereaction reaction Product Product Hydroqenation, l Hydrogenation,

Hydmqmm": Oxidation, Etc., ,Oxidution,

Oxidation Etc.

-0ontaininq NGontaininq Derivatives Derivatives 0t Amo- Of Cyanidereaction reaction Product Product N-Gontainlnq Derivatives 0f Amo-reaction Product I.IIIIIIIIIIIIYIIIII-III..-I

so amketulooesins' v IN VENTOR.

JOHN A. i-IENRICKS, JR.

ATTORNEY.

Crotonaldohydel I Patented July 6, 1937 ELECTRODEPOSITION OF CADlVHUM v John A. Henrlcks, In, Chicago, Ill., assignor, by

mesne assignments, to E. I. du Pont de Nemours & Company, Wilmington, Dei., a cor-.

poration of Delaware Application October 1?, 1935, Serial No. 45,404

13 Claims.

This invention relates to the electrodeposition of cadmium from cyanide-cadmium baths, and

- is particularly directed to cyanide-cadmium plating compositions, plating baths, and plating proc- 5 esses which employ, as an addition agent, anisoamketaldoresin whereby a bright, smooth, uniform cadmium deposit is obtained.

It has heretofore been proposed to modify the character of cadmium deposits by the use of orlO ganic addition agents such as sulflte cellulose waste, dextrin, starch, alkylated naphthalene suifonic acids, wool, caffeine, shellac, casein, licorice, glucose, alkali reaction products of heterocyclic aldehydes, furfural, gum arabic, and gelatine.

15 It has been necessary to employ an addition agent and/or a brightener with cyanide-cadmium plating baths, because, without such modifying agents, cadmium deposits of exceedingly poo-r character and appearance are obtained. The

20 properties of electrodeposited cadmium are largely determined by the addition agent and/or.

brightener used, and the,desirability of a cadmium plate is, to a great extent, dependent upon the emcacy of the modifying agents employed.

The properties of a cadmium plate are partly dependent, in commercial practice, upon certain characteristics of the plating bath employed, and these characteristicsban be modified, to some extent, by suitable organic addition agents and/or 30 brighteners. Under strictly controlled conditions,

one can deposit a fairly satisfactorycadmiumplate on a flat cathode with a bath which, in ordinary commercial' practice, would be unsatisfactory.

Under the usual conditions of commercial oper- 35 ation, particularly when recessed articles or articles of irregular shape are to be plated, a bath must have a fairly wide bright current density range and good throwing power if even moderately satisfactory results are to be obtained. The

40 throwing power and the extent of the bright range have been somewhat improved by the use of the addition agents heretofore known.

,While the addition agents hitherto employed have efiecteda considerable improvement in processes for the electrodepcsition of cadmium, the

results obtained have not been all that could be agents are characterized by good throwing power and by a wide bright current density range.

In the accompanying drawing there are shown the relationships extisting between various derivatives which constitute the addition agents of my invention, and there are also shown, diagrammatically, the methods of preparation of the various derivatives.

, Represented by a circle in the upper left-hand corner of the drawing are the starting materials from which my addition agents are derived. The starting materials are designated -ketaldones but, as will be explained below, certain ketaldones are particularly suitable for my purpose.

My preferred starting materials are, generally speaking, aliphatic and carbocyclic ketaldone's, that is aldehydes and ketones, but, as will become apparent hereinafter, the best results are obtained by the use of certain aliphatic and carbocyclic aldehydes and ketones.

The term ketaldonylf has been applied to des ignate the (2:0 group as it appears in aldehydes and ketones in contradistinction to the C=O group as it appears in acids. Of course, the carbonyl group as'it appears in acids,

bonyl group as it appears in aldehydes and ketones, and the expression ketaldonyl group is employed to distinguish the aldehydic and the ketonic carbonyl group from the acidic carbonyl group. The expression ketaldonyl group as used herein designates a carbonyl group in which a third carbon valence is joined to carbon and in which the remaining valence is satisfied by carbon or by hydrogen. Or, in chemical symbols, the "ketaldonyl group" as used herein is of the type wherein R is a hydrocarbon radical and wherein R. is hydrogen, in the case of an aldehyde, or R.

is a hydrocarbon radical, in the case of a ketone. It will also be understood that the ketones and aldehydes themselves are referred to herein as ketaldones in accordance with this terminology.

Thestarting materials which I employ are, broadly, ketaldones. While I may use-aldoses', ketoses, heterocyclic aldehydes and ketones or any other such ketaldones, I prefer to use aliphatic 6 than two hydroxyl groups and preferably should contain at least two carbon atoms. More specifically, I prefer to employ ketaldones which contain only carbon, hydrogen, and oxygen, which contain at least two carbon atoms, and in which the hyl drogen-oxygen ratio is greater than that of water.

As is illustrated in the drawing, the starting materials, the ketaldones, are reacted with ammonia or an amine, in alkaline solution, to pro- 15 duce an amo-reactionproduct. It will be observed that amo is used to designate both ammonia and an amine. is will be noted hereinafter, the amo-reaction products of the ketaldones are very similar in their physical and 20 chemical characteristics. They all contain nitrogen, and all are, apparently, complex mixtures. I have, accordingly, designated these reaction products amketaldoresins. The nature of the products and the nature of the reaction will be discussed in more detail hereinafter.

The amketaldoresins may subsequently be modified by hydrogenation, oxidation, halogenation, or other such treatment which does not destroy the essential character of the product, to yield 30 nitrogen-containing derivatives which are effective as addition agents. These derivatives are very similar to the amketaldoresins, ordinarilydifl'ering slightly as to color, solubility, and degree of effectiveness as addition agents. The

35 amketaldoresins and these derivatives are herein designated isoamketaldoresins". In other words, the isoamketaldoresins are the amine or ammonia reaction products of aldehydes or ketones, or nitrogen-containing derivatives of such products 40 produced by hydrogenation, oxidation, and the like. As a definition for thepurposes of this application then, the isoamketaldoresins are addition agents for cyanide-cadmium plating and are amketaldoresin derivatives. which contain 4 nitrogen and in which the carbon skeleton of 50 garding the members of the illustrated aldacet the amketaldoresin is unmodified. A preferred group of ketaldones, the aldacet are illustrated in the upper right-hand corner of the drawing. More will be said hereinafter reequilibrium. As is shown in the drawing, the

aldacets, like the ketaldones generally, are reactedwith ammonia, an amine, or cyanide to produce an amketaldoresin. The particular amketaldo- 55 resins produced from the aldacets are designated herein, the amaldacets.

The amaldacets may be reacted, as were the amketaldoresins generally, with hydrogen, oxygen, halogen, or the like to produce nitrogen- 0- containing derivatives. These derivatives, jointly with the amaldacets, are, of course, isoamketaldoresins derived from the aldacets, and this group,

-of similar materials, the amaldacets and their nitrogen-containing derivatives, is termed the 65 isoamalclacets.

The ketaldones which I employ as starting materials are reacted in weak alkaline solution with an amo to produce an amo-reaction product which constitutes an addition agent of my inven- 70 tion. As will be noted hereinafter, the use of cyanide is considered substantially equivalent to reacting the ketaldones with amoes in alkaline solution.

The isoamketaldoresins are preferably derived from the aliphatic ketaldones termed the a dacets. The derivatives ofthealdacets are typical of the isoamketaldoresins, and their preparation will be described below in some detail as illustrative of the isoamketaldoresins generally.

The aldacets comprise the aliphatic aldehydes: acetaldehyde, aldol, crotonaldehyde, and paraldol. In dilute alkaline solution the aldacets appear to exist in equilibrium, any one of the aldacets leading to the production of all at a rate of conversion apparently depending upon the specific aldacet first present. The aldacet equilibrium is illustrated in the upper, right corner of the drawing.

Referring to the aldacet equilibrium in more detail, it is noted that acetaldehyde in dilute alkaline solution is quickly converted to aldol thus:

. H H n n H n H n 1. 11-27-4 34- --Ai-( J=O r: H-l- =0 e it 1!! in l.

The aldol may lose one molecule of water and become crotonaldehyde, thus:

' n H n H The aldol may condense to form paraldol, thus:

converting to aldol. The aldol may go to paraldol or to crotonaldehyde. The aldol might also go back to acetaldehyde, but only to a small extent. The paraldol may go back to aldol, or it may lose water and go to crotonaldehyde, though this latter conversion probably takes place to a very small degree. The crotonaldehyde may form from acetaldehyde, aldol, or paraldol, and, by gaining water, may revert to any of them, though it is likely that it would move largely by way of aldol.

As is seen in the drawing, then, we may consider the aldacets as being in equilibrium. This equilibrium will, according to my belief, be substantially the same regardless of which of the four substances are initially added to the cyanide solution, though, as will hereinafter be noted, the aldacets are not entirely equivalent and it is possible that some of the aldacets in dilute alkaline solution form this aldacet equilibrium rather slowly or move more rapidly in certain directions than in others.

While I have mentioned only acetaldehyde, aldol, crotonaldehyde, and paraldol as members of this sub-genus, I may use any condensation product of acetaldehyde in dilute alkali solution. Another aldacet is paraldehyde. Ordinarily'paraldehyde is considered as forming only'in acid solutions, but I have reason to believe that at least some paraldehyde forms in the discussed aldacet equilibrium. Paraldehyde is apparently very slow to convert to other aldacets and probably because of this fact is none too satisfactory a starting material.

Aldol, acetaldehyde, crotonaldehyde, and paraldol are the only commercially available aldacets at the present time. For practical reasons,

dones is put into alkaline or alkali metal cyanide solution. Generally then, one might say that the aldacets are aliphatic aldehydes from the group consisting of acetaldehyde and its condensation of equilibrium products in alkaline and alkali metal cyanide solutions.

As a definition for the purposes of this application; then. the aldacets are reversible equilibrium-condensation products of acetaldehyde in alkaline solution and particularly in alkaline solutions such-as those of the following Examples I and X. i

As will be noted in detail hereinafter, the aldacets are not entirely equivalent for my purposes but are substantially so. Crotonaldehyde, for example, seems to lead to slightly lower yields. This may be attributable to the fact that crotonaldehyde is but slowly converted to the necessary form, or to some other now unknown cause.

As is above indicated, there is considerable uncertainty as to the extent and nature of the conversion of some aldacets to others. All of the evidence now. available to me substantiates the putative theory above advanced as to the nature of the aldacet equilibrium. but it will be understood that direct exper mental evidence is obtainable only with great difiiculty. In most instances the aldacet e uilibrium exists for only a short time, some further action quickly taking place to form res ns. That the aldacets are in some kind of equilibrium is relatively certain. but the proportions of individual aldace s nd th rates of conversion have, to date, defied exact determination. a

It is clearly to be understood that the above description of the relations between the initial materials is for purposes of illustration and that I do not intend to be limited in any way thereby, because the chemistry of these compounds is intricate and obscure. and because my results are obtained entirely apart from theoretical considerations. It is also to be understood that while I refer to aldol. acc -aldehyde. crotonaldehyde.

and paraldol as resultin from the cond nsation of acetaldehvde in alkaline solutions, I do not wish to be limited thereby. as I may use aldol. acetaldehyde. crotonaldehyde; and 'paraldol w ch have been made in any manner.

Turning now to a consideration f the amketaldoresins pr duced from the a dacets. it is first noted that the specific amke a doresins produced by the reaction of the aldacets with amoes or cyanide in alkaline solutions are termed amaldacets. The amaldacets are almost indistinguishable from one another in physical and chemical properties though, as will be noted hereinafter, they differ slightly from one another as to their efficiency as addition agents for cyanide-cadmium plating.

It is to be noted that the term reaction" is used to express whatever occurs when the ketaldones, or specifically the aldacets, are treated in alkaline solution with cyanide or with an amo.

- The term reaction" is used to distinguish from "com? nsation" as used above with reference to the aldacet equilibrium though, in fact, the reaction probably includes both polymerizations and condensations.

The amaldacets as well as the amketaldoresins contain nitrogen as determined by the Kjeldahl method. In the amaldacets thenitrogen is present in about the ratio of one nitrogen atom to each two molecules of aldol (four of acetaldehyde, one of paraldol, etc.). I have been unable to determine how the nitrogen is located in the amaldacet molecules, and insufficient evidence is available to warrant any assumptions. Y

That the amaldacets are not simple compounds, but are complex mixtures, is evidenced by the fact that portions are water-soluble, other portions chloroform-soluble, etc. It seems probable that the amaldacets are the result of many intricate polymerizations, condensations. and reactions. There may be some condensation products which are not combined with nitrogen, but the fact that a molecular proportion,or an excess. of an amo or of an alkali metal cyanide, to aldehyde give the best results, leads to the belief that the amount of such uncombined products is relatively small. The reaction which leads to the amaldacets takes place, I believe, between ammonia, an amine, or possibly CN- and one or more of the aldacets. This reaction is illus-.- trated in the drawing by dashed lines;- The aldacet. or aldacets, which react with the nitrogen compound may go first to some other and unknown form and then react; I conceive of the reaction as withdrawing one, or more, of the aldacets from the equilibrium with the result that the remaining aldacets move towards the removed materials to restore the equilibrium, and are so all finally utilized.

I have reason to believe that two or more of the materials in equilibrium react with cyanide to roduce the final product, or else the one which reacts with the cyanide moves through a number of different paths to produce a number of final products. This is evidenced by the fact that the reaction product is a mixture of senarable materials. More is said of this separability hereinafter. I 1

To illustrate the production of the amaldacets by the reaction of aldacets with ammonia or amines, the following specific examples are given:

Example I Example II A similar amaldacet was produced by reactin equimolecular proportions of aldol and monoethanolamine. A product exceedingly similar to the one of Example I was produced.

Example III One-half mole of monoethanolamine and one mole of aldol were reacted at temperatures be- This amaldacet protween 30 and 40 C. The product was not as soluble as the product of Example II, and it was not as satisfactory an addition agent for use in cyanide-cadmium'plating.

Example I V Equimolecular proportions of aldol and diethanolamine were reacted at room temperatures. A product very similar to those of the above examples was produced, the product of this example, however, being slightly less soluble than the product of Examples I and II.

Example V Example VI Aldol was treated with ammonia gas by bubbling the gas through the aldol until no further reaction was noted. The reaction product was rather difilcultly soluble, and was only a moderately efiicient addition agent for cya de-cadmium plating baths.

Example ,VII

Equimolecular proportions of crotonaldehyde and ammonium hydroxide were reacted. The reaction product was very similar to that ofthe preceding example. After several days, the amaldacet of this example solidified, becoming much less soluble.

Example VIII Qrotonaldehyde and ammonia gas were reacted at about twenty-five degrees centigrade. vThe product was very similar to that of the preceding example. After a few days the product of this example solidified to a brittle, red resin.

Example IX Acetaldehyde was treated with an excess of gaseous ammonia. An amaldacet similar to that of the preceding example was obtained.

While I have shown the reaction of the aldacets with ammonia, ammonium hydroxide, and with certain amines in the above examples, it will be understood that other amoes may be used. I may. for instance, prepare the amaldacets by treating the aldacets with amines such as the glucamines, for instance, glucamine and methyl glucamine, or aliphatic amines, for instance, methyl ethylamine, methylamine, and ethylamine.

While the amaldacets may be prepared by conducting the reactions of the above examples at rather widely varied temperatures, I prefer that Y the reaction be performed at temperatures between about thirty and fifty degrees centigrade. If much lower temperatures be maintained, the reaction products will tend to contain insoluble or relatively inactive constituents. Similarly, the reaction temperatures should not be permitted to r se too high, because, when the reaction proceeds at high temperatures, the reaction product may contain insoluble constituents and .may have none too great an efliciency as an addition agent.

It is generally preferred to employ an equimolecular proportion, or an excess, of amine to aldehyde. As will be noted by comparing Examples II and III,-less satisfactory amaldacets are produced when less than an equivalent amount of amineis used.

Instead of preparing the amaldacets by the direct reaction of ammonia or amines with the aldacets, they may be prepared by reacting the aldacets with alkali cyanides.

When the aldacets are'treatedwith liquid by drocyanic acid, some slight reaction apparently occurs, but the product has but little, if any, activity as an addition agent in cyanide-cadmium plating baths. From this fact, I have concluded that when the aldacets are reacted with alkali metal cyanides, no great portion of the reaction product contains the CN group.

The cyanides are known to hydrolize to produce ammonia and fonnates according to the following illustrative reaction:

. KCN+ 2HzO NI-Ia+HCOOK It seems possible, accordingly, that the cyanide is hydrolyzed, and that the aldacets react with the ammonia which is formed. This hypothesis is supported by the fact that the odor of ammonia is apparent throughout the reaction.

This hypothesis is further supported by the fact that the reaction products of the aldacets with amoes and with cyanide are very similar.

While very similar. the reaction products of aldacets with alkali metalcyanides are somewhat more desirable than the reaction products of the aldacets with amoes.

It, as I have assumed, the reaction with cyanide amounts to' a reaction with ammonia by reason of the hydrolysis of the cyanide, it is surprising that such a difference in the amaldacets should exist. It seems possible, however, that the differences are attributable to the fact that in an alkali metal cyanide solution the ammonia is somewhat less available. It is possible, of course,

that some of the aldacet reacts with the cyanide directly or with some intermediate product of the hydrolysis. It seems probable, however, that the reaction occurs largely between the aldacet and the, ammonia produced by hydrolysis of the alkaline cyanide solution.

The following specific examples illustrate the production of the amaldacets by the reaction of aldacets with an alkali metal cyanide.

Example X Five parts, by weight, of technical aldol were added to a solution containing three parts, by

weight, of sodium cyanide in ten parts, by weight, of water. The reaction receptacle, to

which the aldol was added, was provided with a water-cooling means, and convenient means were provided for heating the receptacle as re quired. By adding the aldol slowly and employing the cooling means, the temperature of the reaction mixture was held between 45 to 50 C. This temperature was maintained for about two and one-half hours, cooling or heating the receptacle as required. As the aldol was added,

' and for a time thereafter, the heat of the reaction Later it became necessary to supobtained constitutes oneproductof my invention. It is a thick, mobile liquid, dark red in color.

In order to purify and concentrate this product,

- the solution, after being allowed to cool, was made neutral to litmus with a dilute solution of sulfuric acid. The acid solution consisted of one part by volume of water toone part by volume of concentrated sulfuric acid. There was then added an excess of ten per cent over the volume of dilute acid required to neutralize the solution. Sodium sulfate was precipitated, and the excess acid used depressed its solubility. The temperature was not allowed to go above 50 C. during this neutralization treatment. Hydrocyanic acid gas was evolved during the treatment and means were provided for disposing of it.

The acid treated solution was allowed to stand for several hours and a dark red fraction rose to the top. This top layer was removed and centrifuged.

The separated top layer, which constitutes a preferred product of my invention is aviscous liquid, dark red in color, and it has a specific gravity of about 1.20. At temperatures as low as --17 C. it remains liquid, but at the temperature produced with a freezing mixture of solid carbon dioxide and-acetone (below 80 C.) a brittle solid, formed. My product is substantially insoluble in such solventsas ether, benzene, and petroleum ether. It is, however, completely soluble in alcohol and acetone.

The products of this example are entirely soluble 'in cyanide plating baths up to about three grams per liter. One characteristic of both the final product and the unseparated reaction mixture is that when used in cyanide cadmium plating baths they exhibit the property of causing a bright deposit of cadmium. Thischaracteristic serves admirably for the identifi cation of my novel products.

The amaldacets of this example are not chemical compounds, but are mixtures as is evidenced by the fact that portions of the products are water-soluble and a smaller portion of the products is chloroform-soluble. When used as an addition agent in electroplating cadmium, the

water soluble portion exhibits the property of promoting the formation of a bright finish on recessed parts of an article. The water insoluble portion seems to exercise its major influence on the brightness of the less recessed parts .of the article. The chloroform soluble fraction is very active as an addition agent, but when used alone it is not satisfactory as it causes streaks and stains on the plated article.

The temperature of the reaction is relatively important as the yield of the product and its activity as an addition agent seem. to be greatly influenced thereby. The best results seem to be obtained with temperatures between about 45 and 50 C. as used in this example. If lower temperatures are used, there is a decrease in the activity of the product as an addition agent.

Below about 30 C. the product rapidly becomes less active with decreases in temperature. If temperatures substantially above 50 are used,

' the yield of active material is smaller. 'At about 75 C., for instance, about one-half of the product is an insoluble resin without much value as an addition agent. Generally, I may use temperatures from about 30 C. to about 75 C., though more specifically I prefer to keep the reaction temperature between about 45 and 50 C.

The separation by neutralization with acid apparently non-crystalline, is,

as the reaction is complete, the reaction product may be heated to rather high temperatures without substantial damage resulting. V

In the examples, sulfuric acid is employed for removing excess sodium cyanide by converting it to sodium sulfate which then acts to salt out the addition agent. Obviously other acids can be used which lead to a similar result, and moreover, still othermeans for removing the, excess sodium cyanide will readily occur to those working in the art.

' While I may use any of the aldacets as a starting material, I prefer to use aldol because it is readily obtainable commercially at the present time and because it leads to somewhat higher yields than do some of the other aldacets, crotonaldehyde and paraldehyde for instance. Aidol is also advantageously employed by reason of its being less volatile than acetaldehyde and more easily handled than paraldol which is a solid.

As an example-of the preparation of an aural-- dacet from another aldacet, I give the following:

Ewample XI t the product was allowed to cool.

- The resulting amaldacet solution constitutes one product of my invention.

The reaction mixture is preferably concentrated by treatment with dilute sulfuric acid, as described in Example X. The product is substantially identical with the concentrated product of Example X described in detail above.

It is noted that in Example XI'a smaller ratio of cyanide to aldehyde was used than in Example X. This seems to lower the yield of active material somewhat. Generally, the best. results are obtained when the aldehyde and cyanide are used in substantially molecular proportions, but a latitude is permissible.

If less of the alkali metal cyanide be used. I

the product will be less active, while if an excess of alkali metal cyanide be used, no particular damage results. When the product is concentrated by neutralizing with dilute sulfuric acid,v the excess of cyanide, over that required tofo'rm'" the reaction product, is converted to alkali sulfate and hydrocyanic gas, both of which are separated from -the product.

The period of time during which the reaction temperature is maintained may be widely variedperature should be maintained for not less than about one-half hour, and I prefer to maintain it for not less than about four hours to obtain a product of the highest activity. 1

Considering the application of the isoamketaldoresins as addition agents in cyanide-cadmium plating, there are set forth below a number of' illustrative cyanide-cadmium baths employing, for purposes of illustration, certain amaldacets as addition agents.

. If the time be too long, a product of While my addition agents are effective in any customary cyanide bath, I prefer to use; .baths of the kind set forth in U. S. Patent 1,681,509 to Mr. Leon R. Westbrook. These baths are of the cyanide type. and contain a small amount of a compound of ametal of the iron group having an atomic weight greater than fifty-eight. Ti'le details as to the formulation and use of these baths may be found in the said Patent 1,681,509 and need not be duplicated here.

The plating baths of the said Patent 1,681,509 are modified only by employing my novel addition agents in lieu of the addition agents, goulac, dextrin, starch, etc., mentioned therein.- While the plating processes described in the said Patent 1,681,509 lead to a bright, ha'rd, dense, and smooth deposit of cadmium, and while the invention,

therein described and claimed has been widely accepted by the art because of its merit, the substitution of my addition agents for those in the patent results in a cadmium deposit of even greater smoothness, uniformity, and brightness.

The following specific example illustrates the use of a preferred amaldacet with a preferred plating bath of the type disclosed in the said Westbrook Patent 1,681,509.

Example XII A concentrated amaldacet produced according to Example X was employed as an addition agent in acyanide-cadmium bath made up as follows:

. Grams per liter Sodium cyanide (NaCN); 130 Cadmium oxide (CdO) 43 Sodium sulfate (NaaSO4) 50 Cobalt sulfate (C0SO4-7H2O) 10 Addition agent 1.4

About one-hundred and ninety liters of plating solution were made up and used in the customary way to plate some large, fiat articles, several square feet in area, with a cadmium deposit about five-thousandths of an inch thick. After washing with water, the articles were examined and found to have a perfectly smooth, mirror finish. It is, of course, very difllcult with prior art processes to obtain even a fairly smooth finish when so thick a deposit of cadmium is plated.

The bath of this example displayed good throwing power and a wide bright current density range.

The concentrated amaldacet of Example X may satisfactorily be employed, in widely varying amounts, but I usually prefer .to use between about eight-tenths and two grams per liter. The proportion of the amaldacet used above, one and four-tenths grams per liter, is-about an optimum under the conditions of this example.

Of course, I may use other compounds of metalsof the iron group having an atomic weight greater than fifty-eight, such as nickel, copper, etc., as disclosed in the heretofore mentioned Patent 1,681,509, but the use of cobalt compounds has led tothe best results.

The amaldacet solution obtained in Example X by the reaction of an aldacet with an alkali metal cyanide constitutes, without further treatment, a product of my invention. The following examples illustrate the use of this less concentrated product:

Example XIII 'I'he product of Example X, obtained by reacting aldol and sodium cyanide. was used as an addition agent in a bath made up as follows:

I Grams per liter Sodium cyanide (NaCN) 130 Cadmium oxide (CdO) 43 Sodium sulfate (Nazsol) 50 Cobalt sulfate (COSOr'IHaO) 10 Addition agent 5 The concentrated product obtained in Example XI was employed as an addition agentin a bath made up as follows:

Grams per liter Sodium cyanide (NaCN) 120 Cadmium oxide (CdO); 45 Sodium sulfate (Nazsol) 60 Nickel sulfate (Nlsolwmo) 1 Addition agent were obtained.

The considerations as to the proper quantity of the addition agent of this example are substantially the same as the considerations above 'Results comparable to those of Example XII noted in connection with Example XII. This i would be expected, of course, because of the fact that the concentrated products of Examples X and XI are substantially identical.

Example XV The amaldacet-containing product obtained in Example XI by the reaction of acetaldehyde and sodium cyanide was employed in a hath made up as follows:

. Grams per liter Sodium cyanide (NaCN) 120 Cadmium hydroxide (Cd(OH)2) 50 Sodium sulfate (NMSOO 60 Nickel sulfate mlsol-mlm Y l Addition-agent 2 'When used as a plating bath, t s solution produced uniformly bright, mirror-11k cadmium deposits.

I desire thatit be clearly understood that the whole disclosure of the heretofore mentioned Patent 1,681,509, as well as that of U. S. Patent 1,564,413 to Clayton M. Hoff, cited therein, is to be considered, in its entirety, as an integral part of my disclosure, as my novel addition agents co-act with the cyanide-metal compound baths therein to produce a result unexpected from an examination of the attributes of either by addition agents or the baths of the said patent, for, as will presently appear, baths of such high concentration cannot be used to advantage without the metal compounds added by Westbrook.

While I have discussed above the use of baths of the Westbrook type,-I do not wish to be limited thereto. I prefer twuse-thembecause of certain commercial considerations, and because they may be more concentrated, but excellent Example XVI A concentrated amaldacet produced according to the process of Example X was employed as an addition agent in a-bath made upas follows:

Grams per liter Cadmium oxide (CdO) 26 Sodium cyanide (NaGN) 87 Addition agent 0.7

This bath was used for plating several objects at a current density of twenty amperes per square foot The deposit was extremely bright 'and smooth. The number of grams of cadmium oxide in the above bath may be varied betweenfifteen and thirty-five and good results will be obtained. If the bath be too concentrated the deposit will not be entirely satisfactory.

The addition agent is used in about an optimum proportion for the conditions of this example, but I may advantageously employ from about five-tenths to about seventy-five hundredths gram per liter of this agent. The other amaldacets above discussed can, of course, be employed in equivalent amounts.

Example XVII The amaldacet-containing solution of Example X was employed in a cyanide-cadmium bath made portions which exercise a major effect on the less up as follows:

Excellent results were obtained with this bath.

In this bath the number of grams per liter of cadmium oxide may vary between fifteen and forty and excellent results will still be obtained.

As has already been noted with particular reference to the amaldacets produced by the reaction of aldacets with sodium cyanide, my addition agents are not unitary compounds, but rather are mixtures of compounds. The addition agents of Examples X and XI, for instance, are divisible, as above noted, into water soluble portions which exercise a major effect on the recessed portions of an article being plated, and water insoluble recessed portions. These portions may, if desired, be used alone or may be admixed with other addition agents.

It has also been noted that a chloroform soluble portion of these agents displays great activity as an addition agent, but promotes a streaked and somewhat unsatisfactory deposit. The removal of the chloroform soluble portion is in the nature of a purification, but, in admixture with the other constituents of the addition agent, the chloroform soluble portion does not seem.to act in an appreciably deleterious manner, and it is ordinarily not expedient to efiect its separation.

Considering, now, the application of amaldacets such as those produced according to the procedures of Examples I through IX, there are given below a few specific examples illustrating baths and processes employing such addition agents:

Example XVIII A cyanide-cadmium bath, of the type disclosedin the above mentioned Patent 1,681,509, was

ample I .as an addition agent:

Grams per liter Sodium cyanide (NaCN) Cadmium oxide (CdO) 43 Sodium sulfate (NazSOO 50 Cobalt sulfate (COSO4-7H2O) 10 Addition agent 1.5

By the use of this bath, smooth, uniform cadmium deposits were obtained. The bath displayed a wide bright current density range and good throwing power. Generally, the results were comparable to those obtained with the'addition agent of Example X in the procedure of Example XII. The cadmium deposit of the present example, however, was not quite as bright as the deposit made up as follows with the amaldacet of 'Ex- I obtained according to the procedure of Example The considerations as to the quantity of addition agent which should be used are the same as those considered above in connection with Example XII.

\ Example XIX Using the amaldacet produced in Example 11 by reacting aldol and monoethanolamine, a cyanide-cadmium bath was made up as follows:

' Grams per liter Cadmium oxide (CdO) 26 Sodium cyanide (NaCN) 87 Addition agent 1.2

Very good results were obtained by the use of this bath. It is to-be noted, however, that the addition agent of this example is slightly less satisfactory than the one used above in Example XVIII.

Some of the heretofore mentioned amaldacets are not readily soluble in cyanide-cadmium plating baths, and it is desirable that they be dispersed in the baths. With the isoamketaldoresins generally, likewise, it is expedient to disperse the addition agent if dimculty is encountered in dissolving an optimum quantity. The addition agents may be dispersed and their dissolution aided by adding them to a cyanide-cadmium bath in a suitable solvent, such as alcohol or acetone. It may sometimes be found desirable to reduce the addition agents to a finely divided state, or to use them in conjunction with such dispersing agents as saponin, gum arabic, and sulfite .cellulose waste.

Example XX The product of Example VI, prepared by treating aldol with ammonia, was added to a cyanidecadmiumbath in alcohol solution. The bath was made up as follows:

. Grams per liter Sodium cyanide (NaCN) 130 Cadmium oxide (CdO) 43 Sodium sulfate (Na-2804) 50 Cobalt sulfate (CoSO4-7H20) Addition agent 2 given in the foregoing examples. It is relatively 7 h is simple, of course. to determine the range of proportions in which the addition agents exercise an optimum effect, and it therefore seems unnecessary to set forth in detail the proportions in which all of the addition agents mentioned herein are most satisfactorily used.

In the foregoing, the amketaldoresins derived by reacting an aldacet with ammonia, an amine, or cyanide have been discussed in some detail with reference to their preparation. their proper- I ties, and their applications as addition agents in cyanide-cadmium plating. 7 considered above are, in many respects, typical of the amketaldoresins.

The amaldacets are, of course, derived from certain aliphatic ketaldones: the aldacets. Be-

low are discussed typical amketaldoresins derived from other aliphatic ketaldones and from carbocyclic ketaldones.

The following typical aliphatic ketaldoneswere tried as starting materials for the production of isoamketaldoresins. The aldacets are included for purposes of comparison. The compounds in the respective lists are given in about the order of their desirability as starting. materials.

Aldehydes Aldol Acetaldehyde Crotonaldehyde Paraldol Propionaldehyde a-ethyl p-propyl acrolein Butyraldehyde Acrolein Citral Citronellal Hexadecoic aldehyde Isobutylaldehyde Ketones Diethyl ketone Methyl n-propyl ketone Methyl ethyl ketone Diacetyl Light acetone oil Heavy acetone oil Isobutyl ketone Acetone Iso amyl ketone Considering more specifically the preparation of amketaldoresins from the above aliphatic ketaldones, the following specific examples are given:

Emample XXI Equimolecular proportions of monoethanolamine and propionaldehyde were reacted at room temperature. A soluble resin was obtained which, when employed in baths such as those of Examples XII and XVI, displayed activity as an addition agent but was none too satisfactory.

Example XXII Methyl ethyl ketone was treated at room temperature with gaseous ammonia. The resulting reaction product displayed activity as an addition agent in cyanide-cadmium plating baths.

Example XXIII Five parts by weight of propionaldehyde were mixed with three parts by weight of sodium cyanide and ten parts by weight'of water. The mixture was maintained at a temperature of about 50 C. for two hours and then allowed to cool, There was a change in the appearance of The products thusthe mixture during the reaction period. The reaction product was a homogeneous, mobile liquid,

light yellow in color. This reaction mixture constitutes a product of my invention.

The addition agent of this example was used in a cyanide-cadmium bath such as that of Example XII, the addition agent 01 this examplebeing used at a concentration of about 1.5 cc.

per liter in lieu of the addition agent of Ex-- ample XII. A bright, lustrous cadmium deposit was obtained, and the bath was characterized by good throwing power and a relatively 'wide bright current density range.

Example XXIV Diethyl ketone was treated with sodium cyanide according to the procedure of Example XXIII,

.and the reaction product permitted to stand a few days. The reaction mixture separated into two layers: a colorless lower layer, which is probably sodium cyanide solution, and an upper layer which is light yellow in color. While I may use both layers mixed together as an addition agent, I prefer to separate, and use, the upper layer.

The yellow upper layer was used in a cyanidecadmium bath of the type shown in Example XII at an optimum concentration of 5 cc. per liter. Excellent results were obtained. The colorless lower layer displayed no appreciable activity as an addition agent. I

Example XXV Methyl ethyl ketone was treated with sodium cyan de according to the procedure of Example XXIII and then allowed to stand a few days. The reaction mixture separated into a lower,

' light yellow layer, and a small upper layer, dark red in color. Again I may use the mixture, but I prefer to use the upper layer.

The upper, dark red layer was used at a concentration of 6 cc. per liter in a cyanide-cadmium bath oi. the type shown in Example XII with fair results. The lower, light yellow layer was not substantially effective as an addition agent in cyanide-cadmium plating Example XXVI Diacetyl was treated with sodium cyanide according to the procedure of Example XXIII, and a homogeneous liquid was obtained.

The diacetyl-cyanide reaction product was employed at a concentration of 2 cc. per liter in a bath of the type shown in Example XII with good results.

Example XXV'II Methyl n-propyl ketone was treated with sodium cyanide according to the procedure of Example XXV. A colorless upper layer and a color- Example XXVIII Acetone was treated with sodium cyanide according to the procedure of Example XXV. After. standing three weeks, a light-red lower layer and a dark-red upper layer formed. I

' ferent character from the agents prepared from may use the mixture as an addition agent,but I prefer to merchandise the upper layer separately,

light-redlower layer was somewhat effective as-an addition agent in a cyanide-cadmium bath of the type shown in Example x11. When used as an addition agent in a bath of the same type, the dark-red upper layer was found quite satisfactory at a concentration of 20 cc. per liter.

Example XXIX Butyraldehyde was treated with sodium cyanide according to the procedure of Example XXV.

The two layers which formed are both active as addition agents, and I may use either or the mixture.

The lower layer gave good results as an addition agent at a concentration of 15cc. per liter in a cyanide-cadmium bath of the type shown in Example XII. The upper layer produced even better results at a concentration of only 5 cc. per liter in a cyanide-cadmium bath of the same type.

Example XXX Hexadecoic aldehydeswas treated with sodium cyanide according to the procedure of Example XXIII, the mixture of aldehyde and cyanide being maintained at about 50 C. for four hours. The reaction mixture was allowed to stand overnight and was found to have separated with a top layer of nearly black cyanide reaction product. It is noted that the original aldehyde was light yellow in color.

The lower layer had no appreciable effect as an addition agent in a cyanide-cadmium bath of the type shown in Example XII. The upper layer was rather diflicultly soluble, but at its optimum concentrationof 5 cc. per liter, it served as an addition agent'in a cyanide-' cadmium bath of the same type. The top layer being poorly soluble, it should be dispersed in the bath after the manner hereinbefore suggested.

When aliphatic ketaldones are used as starting materials, a ketaldone should be selected which contains at least two, carbon atoms. Formaldehyde, with but one carbon atom, stands in a unique position with respect to aldehydes generally. Its dissimilarity to the other aldehydes is, of course, generally recognized.

Two hundred cubic centimeters of a forty per cent solution of formaldehyde was slowly added to a solution of sixty grams of sodium cyanide in eighty cubic centimeters of water. The temperature rose rapidly, and the reaction vessel was cooled to maintain a temperature of about 45 to 50 C. After about two-thirds of the formaldehyde was added, the addition of the remaining one-third produced no appreciable effect. After about ten minutes, however, the reaction mixture became hot and it was necessary to cool it. After the reaction was complete, a dark colored product was obtained. This product was tried as an addition agent, using from one to ten grams .per liter, in a bath of the type shown in Example XII, and it was found that the product other aldehydes, I prefer to employ ketaldones which have more than one carbon atom.

As the aliphatic ketaldones contain more and more carbon atoms, they appear to become less desirable as starting materials for the production of amketaldoresins.

factory-as starting materials for the production of addition agents, but the agents tend to be somewhat insoluble. They may, of course, be dispersed in the bath, but it is ordinarily preferable that the agents be readily soluble in the amounts required.

Above about nine carbon atoms the aliphatic ketaldones become somewhat less desirable as starting materials. Hexadecoic aldehyde, for instance, with sixteen carbon atoms led to the production of a relatively insoluble, though operative, amketaldoresin. I prefer, accordingly, to employ aliphatic ketaldones containing between two and nine carbon atoms. This terminology includes acetaldehyde, for example, as' a two carbon atom compound and citral as a nine carbon atom compound. I especially preferto employ those aliphatic ketaldones of two to nine carbon atoms Citral and citronellal, for example, with nine carbon atoms are quite satiswhich contain no more than two hydroxyl groups. I have found that it is not desirable that the aliphatic ketaldones contain carboxyl groups.

Moreover, the elements sulfur and nitrogen are preferably absent from the aliphatic ketaldones which I employ as starting materials for the production of amketaldoresins. I especially prefer to use aliphatic ketaldones which contain only carbon, hydrogen, and oxygen, and in which the hydrogen-oxygen ratio is higher than that of water.

The formula of the aliphatic ketaldones which I prefer to employ may -be expressed in a somewhat specific manner, as follows:

CnHaOn-(Hy) Wherein n equals two or more, though preferably no more than nine; wherein a: is two or more;

invention to use such ketaldones as ketoses andv aldoses.

When carbohydrates which contain an aldehyde or'ketone group are treated with an amo or with an alkali metal cyanide, products similar to those above may, with some difiiculty, be pre- I pared. The amketaldoresins thus produced, however, are of a different order of effectiveness than the preferred amketaldoresins.

The following example illustrates the produc- I tion of an amketaldoresin from a carbohydrate which contains a ketaldonyl group.

Example XXXI Glucose was treated with an alkali metal cyanide by adding 123- grams of glucose to a cyanide solution made by adding 3.3 grams of sodium cyature was maintained at about 45 to 50 C. for eighteen hours and was agitatedintermittently. During the period of treatment, a faint odor of ammonia was observed.

' nide to 10 cubic centimeters of water. The mixample.

dition agent in cyanide-cadmium baths of the type'shown' in Example XII in various concentrations up to ten grams per liter. The addition agent effected a considerable change in the character of the cadmium deposits,-but was none too satisfactory. It is noted that the baths containing the addition agent were reddish-yellow in color.

For purposes of direct comparison, glucose was employed as an addition agent for cyanide-cadmium baths of the same type and in the same concentrations as were the products of this exthan its cyanide-reaction product. It is noted that the baths containing-glucose were lightyellow in color.

The amketaldoresins prepared from the aliphatic ketaldones have been discussed above in some detail, and it is now proposed to discuss briefly the preparation 01 amketaldoresins from carbocyclic ketaldones.

The amketaldoresins may be prepared by the treatment of carbocyclic ketaldones with an amo or cyanide according to procedures similar to those above discussed.

The following carbocyclic ketaldones, tried as starting materials for the production of amketaldoresins, are listed in the approximate order of their desirability.

1. Cyclohexanone 2. Methyl cyclohexanone Benzoin Benzaldehyde Anisic aldehyde Cinnamic aldehyde Quinone Vaniilin Qrtho-ortho dicarboxy benzoin In order more fully to describe the production of the amketaldoresins from the carbocyclic ketaldones, the following illustrative examples are given:

Example XXXII Equimolecular proportions of monoethanolamine and benzaldehyde were reacted at room temperature. The product displayed activity as an addition agent in a cyanide-cadmium plating bath of the type shown in Example XII.

Example XXXIII Gaseous ammonia was passed into benzaldehyde until the reaction was complete. The amketaldoresin produced was found to have activity as an addition agent in a cyanide-cadmium bath of the type shown in Example XII.

Example XXXII/ Glucose itself was much less effective the cyanide solution a precipitate of some relatively insoluble material formed. After a few hours most of this precipitate had dissolved. The

reaction mixture was employed quite successfully with a cyanide-cadmium bath of the type shown in Example XII.

Benzaldehyde is known to form benzoin in alkaline solution according to the following:

. ,UEPI QZEAO As the starting materials, benzaldehyde and benzoin, are difiicultly soluble, I added two carboxyl groups to benzoin thus:

COOH COOH [jizi This ortho-ortho dlcarboxy benzoin was much more soluble than benzoin, but it was none too satisfactory as a starting material for the pro-' duction of addition agents. Ortho-ortho dicar- .boxy benzoin was treated with cyanide, as in the above examples, and the product was found to possess some activity as an addition agent in cyanide-cadmium baths.

The other carbocyclic compounds above listed may be similarly treated with an amo or cyanide according to the above procedures with good results. It is noted that instead of usingmethyl cyclohexanone, I may use other alkyl substituted cyclohexanones. I may, of course, use more than one alkyl substituent.

While generally I may advantageously employ any carbocyclic ketaidone, I prefer to use as starting materials ketaldones which do not-contain a carboxyl group and which do not contain sulfur. Moreover, carbocyclic ketaldones which do not contain nitrogenare ordinarily preferred, because while Michlers ketone, for instance, responds to my broadest definition, it is none too satisfactory a starting material. Specifically, I prefer to employ carbocyclic ketaldones which contain only carbon, hydrogen, and oxygen and in which the hydrogen-oxygen ratio is greater than in water.

The foregoing discussion of the aromatic ketaldones is limited to a preferred group, the carbocyclic ketaldones. It will be understood, however, that my invention in its broad aspects includes the use of cyclic ketaldones generally. I

Example xxxvn Six and one-half grams of freshly distilled furfural was added to a sodium cyanide solution made up of 3.3 grams of sodium cyanide in 10 cubic centimeters of water. Quickly there was produced a red, heterogeneous mixture which 1 was then maintained for six hours at 45 to 50 I C. During the reaction period, a faint odor of ammonia was observed. At the end of the six hours, the mixture ha'd reacted to form a black, tarry, lower layer and a brown, supernatant liquid. The black lower layer is effective as an addition agent, and it constitutes a product of this invention.

The reaction mixture obtained above was treated with an excess of dilute sulfuric acid over that required to react with excess sodium cyanide,

after the procedure of Example X. Upon the addition of acid, a violent reaction took place, and a small amount of a black, liquid tar separated from the upper layer and joined the tar already at the bottom of the reaction receptacle.

The mixture of tars was employed as an addition agent in cyanide-cadmium baths of the type above shown in Example XII. The baths were of a reddish colqr. Excellent results were obtained,

but the agent of this example did not cause the baths to display as extended a bright current density range as did the agents of Example X.

' The agentsof thisexample are rather difiicultly soluble, and it is preferred to add them to cya- 40 nide-cadmium baths in a suitable solvent such as alcohol. An optimum effect appears to be obtained when from about one-half to two grams per liter of the agents are used.

It will be understood that the conditions for the 5 preparation of the furfural-cyanide products of this example may be widely varied. It is preferable that about an equivalent amount, or a slight excess of sodium cyanide be used. It should be noted in this connection that a great excess of cyanide is not satisfactory as, in efiect, the furfural would be present in too small a concentration for the proper reactions to take place.

Furfural was employed as an addition agent for,

cyanide-cadmium baths, of the type used in Ex- 5 ample XII, in various amounts up to about ten grams per liter. After standing for several hours, the baths becamevery dark in color, and appeared black. By strong transmitted light, a small sample of one such bath appeared tohave a dark,

wine color. While furfural, in relatively large amounts, displayed some activity as an addition agent, it was very much less effective than the furfural-cyanide products of this example.

It will be understood therefore that in the production of amketaldoresins no such great departure from equimolecular proportions should be made. It will also be'evident that the reacting materials should not be too dilute.

That the furfural-cyanide products of this example are not merely condensation products in al-' kaline solution is evidenced by their similarity to the products of Example X, by the fact that the odor of ammonia can be detected during the reaction, and by the fact that resins formed by furwere added. A dark-brown, opaque solution was obtained.

The furfural-alkali resin was employed in various amounts as an addition agent for cyanidecadmlum baths of the type shown in Example XII as well as in baths of a similar type which contained no such brightening agent as cobalt or nickel. The baths were a clear, dark-red in color. While these materials displayed a slight activity,

they were not even as effective as untreated furfural. I

There have been considered above a number of isoamketaldoresins, namely, the amketaldoresins. In addition to the amketaldoresins, the isoamketaldoreslns include derivatives of the amketaidoresins, such as their hydrogenation, oxidation, sulfurization, and halogenation products. These derivatives are, of course, characterized by their s-milarity to the amketaldoresins, and by the fact that they contain nitrogen.

Similar derivatives of the amaldacets, together with the amaldacets, are termed isoamaldacets.- The relationships of the isoamketaldoresins, isoamaldacets, amketaldoresins, and amaldacets have been discussed hereinbefore, and, as has been noted above, the relationships are clearly illustrated in the drawing.

I The following example illustrates the preparation of an isoamketaldoresin which has a higher ratio of hydrogen ,to oxygen than have the amketaldoresins:

Example XXXVIII (1) Grams per liter Sodium cyanide (NaCN) 130 Cadmium'oxide (CdO) 43 Sodium sulfate '(Na2SO4) 50 Cobalt sulfate (C0SO4-7H2O) 10 Addition agent 1.2

(2) Grams per liter Cadmium oxide (CdO) 25 Sodium cyanide (NaCN) Addition agent, 0.6

Results comparable to those of Examples XII and XVI were obtained. v

The reduced solution may, of course, be used after the manner in which the aldacet reaction product was used in Examples XIII and XVII.

The reduced amaldacets are slightly more soluble than the untreated amaldacets, and are slightly more active as addition agents in cyanide-cadmium plating.

1-2 I Example xxxlx trations than the corresponding products of Example XI.

Example XL The orotonaldehyde-monoethanolamine reac tion product of Example I was dissolved in alkaline cyanide solution, and zinc dust was added to reduce the product. The product gave results comparable with those obtained in Example XVIII when employed in a similar cyanidecadmium bath.

Example XLI Following the procedure of the, above Example XXXVIII, the propionaldehyde-sodium cyanide reaction product of Example XXIII, was reduced by the use of zinc dust. The reduced product gave results comparable to those of Example XXIII when employed in a similar cyanidecadmium bath.

, Example XLII Following the procedure of the above Example XXXVIII, the benzaldehyde-sodium cyanide reaction product of Example XXXIV was reduced. The reduced product displayed activity as an addition agent in cyanide-cadmium baths of the types shown above.

The other amketaldoresins "disclosed hereto-- iore may be reduced in manners similar to those shown in the above illustrative Examples XXXVIII thru XLII.

In the foregoing examples, zinc dust was employed as a reducing agent largely because of its convenience, but as will be evident, other reducing agents may satisfactorily be employed. I may, for instance, use a reducing agent such as sodium sulfite. It will be understood that the extent of reduction of the amketaldoresins may be widely varied, the hydrogen presumably saturating some or all of the double bonds.

The following examples: illustrate the production of isoamketaldoresins by lowering the ratio of hydrogen to oxygen of amketaldoresins:

Example XLIII The cyanide reaction product of the above Example X was subjected to oxidation by adding thereto ten cc. per liter of 100 volume (30% by weight) hydrogen peroxide. The product thus obtained was concentrated by acidification with sulfuric acid according to the procedure of the above Example X.

Employing the concentrated product as an addition agent, cyanide-cadmium plating baths were made up as follows:

Sodium cyanide (NaCN) 130 Cadmium oxide (CdO) 43 Sodium sulfate (Na-2804) Cobalt sulfate (CoSO4-7H2O) 10 Addition agent 1.2

(2) Gramsper liter Cadmium oxide (CdO) 25 Sodium cyanide (NaCN) 120 Addition agent 0.6

Results comparable to those of Examples X11 and XVI were obtained.

Grams per liter The oxidized solution may, of course, be employed as an addition agent for cyanide-cadmium baths. Results comparable to those of Examples XIII and XVII will be obtained;

The oxidized amaldacets, like the reduced amaldacets, are slightly more soluble and slightly more effective as addition agents in cyanide-cadmium plating baths than the untreated amketaldoresins from which they are derived.

The reduced and oxidized amaldacets are very similar in theirproperties, as has been noted above, and they may advantageously be employed under similar conditions and in similar amounts.

Example XLI V The reaction product of Example In was oxidized, according to the procedure of the above Example XLIII, and the oxidized product concentrated. The oxidized reaction product and the concentrated product produced results comparable with those obtained above with the addi-- tion agent of Example XI.

Example XLV Example XLVI The propionaldehyde-sodium cyanide reaction product of Example IQHII yielded, upon oxidation, a product very satisfactory as an addition agent when used in cyanide-cadmium baths of the type shown above.

. Example XLVII Following the procedure of the above Example XLIII, the benzaldehyde-sod-ium cyanide reaction product of Example XXXIV was oxidized. The oxidized product displayed activity as an addition agent in cyanide-cadmium baths of the types above shown.

The other amketaldoresins disclosed herein may similarly be oxidized to produce addition agents for cyanide-cadmium plating.

While hydrogen peroxide has been particularly mentioned in the above examples as an oxidizing agent, it will be evident to those skilled in the art that other suitable oxidizing agents such as sodium or potassium permanganates may be employed. The extent of oxidation may be widely varied, but it will be evident that the oxidation must not be carried too far. Generally, any amount of oxidation may be employed provided the carbon skeletons of the compounds are not broken up. The oxidized product, of course, should contain nitrogen.

The amketaldoresins may be modified in a number of other ways, as will be evident to those skilled in the art, without a destruction of their properties as addition agents. They may, for instance, be treated with hydrogen sulfide, in which event a somewhat inferior addition agent is obtained. The amketaldoresins, moreover,

- might be halogenated. Generally, the derivatives 'should contain nitrogen, and it is desirable that they be somewhat soluble. They are, of course, characterized by activity as addition agents in cyanide-cadmium plating baths, and many such derivatives of the amketaldoresins may be prepared which are suitable for my purposes.

In general, then, the addition agents suitable.

for use in cyanide-cadmium plating baths according to my invention may be referred to as prereacted addition agents prepared by reacting a ketaldone with an amo in alkaline solution. The

term ketaldone refers, of course, to aldehydes and ketones as is set forth in detail hereinbefore, and the term amo refers to ammonia and amines as in United States Patent 1,961,890 and as set forth in detail hereinbefore.

In order conveniently to merchandise my novel addition agents, I may incorporate them with the dry ingredients employed to make up a plating bath. The resulting dry mixture can then be packaged and sold to the consumer who needs only to dissolve the mixture in water for use.

Again, I may find it desirable to incorporate the addition agent with only one or a few of the ingredients and let the consumer add the other ingredients. Frequently, of course, it will be desirable to merchandise the novel addition agents as such.

While I have disclosed a number of specific cyanide-cadmium baths heretofore, it will be understood that I do not intend to belimited thereby and that the teachings of my invention may be applied to cyanide-cadmium baths generally. I

It will be also understood that I do not intend to be limited to the specific isoamketaldoresins above disclosed, as numerous other such compositions can readily be prepared by those skilled in the art according to the principles of my invention.

This case is a continuation in part of my ,copending applications Serial Nos. 737,610, 737,611, and 737,612 filed July 30, 1934.

I claim:

1. A cyanide-cadmium plating composition containing an amketaldoresin, an amketaldoresin being, as herein set forth, a pre-reacted addition agent prepared by reacting a ketaldone with an amo in alkaline solution.

2. A cyanide-cadmium plating composition containing an amketaldoresin derived from a hetero- .cyclic ketaldone, an amketaldoresin being, as

herein set forth, a pre-reacted addition agent prepared by reacting a ketaldone with an amo in alkaline solution.

3. A cyanide-cadmium plating composition containing an amketaldoresin derived from a carbocyclic ketaldone, an amketaldoresin being, as

herein set forth, a pre-reacted addition agent prepared by reacting a ketaldone with an amo in alkaline solution.- I

4. A cyanide-cadmium plating composition containing an amketaldoresin derived from a carbocyclic ketaldone which contains only carbon, hydrogen, and oxygen, and in which the ratio of hydrogen to oxygen is greater than that of water, I

phatic ketaldone which contains only carbon,

hydrogen, and oxygen, which has no less than two and no more than nine carbon atoms, and in which the ratio of hydrogen to oxygen is greater than that of water,- an amketaldoresin being, as herein set forth, a pre-reacted addition agent prepared by reacting a ketaldone with an amo in alkaline solution.

'7. A cyanide-cadmium plating composition containinga pre-reacted addition agent prepared by reacting a ketaldone with an amo in alkaline solution.

8. A cyanide-cadmium plating composition containing a pre-reacted addition'agent prepared by reacting an aliphatic ketaldone with an amo in alkaline solution.

9. A cyanide-cadmium plating composition containing a metal of the iron group having an atomic weight greater than fifty-eight and a prereacted addition agent prepared by reacting a ketaldone with an amo in alkaline solution.

10. In a process for the electrodeposition of cadmium, the step comprising depositing cadmium from a cyanide-cadmium bath in the pres.- ence of a pre-reacted addition agent prepared by reacting a ketaldone with an amo in alkaline solution.

11. A cyanide-cadmium plating composition containing a pre-reacted addition agent prepared by reacting an aliphatic aldehyde selected from the group consisting of acetaldehyde, aldol, crotonaldehyde, and paraldol with an amo in alkaline solution.

12. A cyanide-cadmium plating composition containing a pre-reacted addition'agent prepared by reacting aldol with an amo inalkaline solution. v

13. In a process for the electrodeposition of cadmium, the step comprising depositing cadmium from a cyanide-cadmium bath in the presence ofan addition agent comprising an amketaldo'resin, an amketaldoresin being, as herein set forth,'a pre-reacted addition agent prepared by reacting a ketaldone with an amo in alkaline solution.

JOHN A. HENRICKS. Jn. 

